1. Field of the Invention
This invention relates to catalytic compositions, and more particularly to catalytic compositions which exhibit a marked catalytic effect on the formation of unsaturated nitriles by vapor-phase reaction of an olefin, ammonia and oxygen or an oxygen-containing gas, particularly on the formation of acrylonitrile by vapor-phase reaction of propylene, ammonia and oxygen or an oxygen-containing gas.
2. Description of the Prior Art
Various catalysts have heretofore been proposed for the production of acrylonitrile by vapor-phase catalytic ammoxidation of propylene. It is known in the art that a catalyst comprising molybdenum and bismuth as primary components and further containing such metallic elements as iron, nickel, cobalt and the like can be used to produce acrylonitrile in relatively good yield. However, when such a catalyst is used under the conditions where the gaseous materials are fed into the catalyst bed at a high space velocity and where the conversion of propylene is increased, the selectivity of the catalyst is so decreased that it becomes difficult to achieve a satisfactorily good yield of acrylonitrile. During our study with the intention of developing a catalyst which is capable of producing acrylonitrile with high selectivity even in the case where the gaseous materials are fed at a high space velocity and where the conversion of propylene is increased, we found and disclosed in our co-pending application (Japanese Patent Application Laid-Open (KOKAI) No. 110997/1979) that a catalyst comprising molybdenum, tungsten, bismuth, lead and oxygen within a certain range of composition can be used to produce acrylonitrile in good yield even under the conditions where both the space velocity of the gaseous materials and the conversion of propylene are increased over the prior art molybdenum-bismuth catalysts.